Diorama artist Lori Nix created
this fantastic artwork for Wired about Harry Potter's last movie. She
detailed the process in her blog My 8x10 Life:

After we got the green light we headed off to Barnes and Noble
in search of hardback Harry Potter books. We then took a ruler and eyed
how large the creepy tree should be, and also what scale figures would
work best standing around the grave. I started immediately making the
tree form out of wire, lots and lots of twisting wire.